1. Field of the Invention
The present invention relates to an improved surgical stapler that prevents refiring of a spent staple cartridge. More specifically, this invention includes an inexpensive, simple and reliable mechanical locking mechanism that prevents refiring of a spent staple cartridge.
2. Description of the Related Art
Before surgical staplers were introduced surgeons had to spend a great deal of time sewing the tissue of patients back together. This was the most time intensive aspect of a surgical procedure. Surgical staplers have decreased the amount of time that a user spends sewing tissue back together.
Another concern is whether the staplers used during procedures are sterile. Reusable staplers, being a relatively complicated mechanical instrument, are difficult to sterilize after use. Hence, it is desired that the surgical stapler be disposable. As more than one surgical stapler may be required in a surgical procedure, for economical reasons disposable surgical staplers having reloadable staple cartridges have been developed.
It is desired that operating room personnel be able to quickly reload a disposable surgical stapler with an unspent staple cartridge during a surgical procedure. This is significant because as the amount of time it takes to reload a stapler is decreased, the amount of time that the whole procedure takes is also decreased. This means the amount of risk to the patient is less during a procedure of shorter duration. For example, the patient will not have to be under anesthesia as long during a shorter procedure. However, delay occurs when a used cartridge is inadvertently reloaded in the stapler or a used cartridge is not removed before an attempt is made to use the stapler.
There are various types of staplers. Some staplers perform the sole function of stapling while other types of staplers also perform additional functions. For example, one type of surgical stapler has parallel rows of staples with a slot for a cutting means to travel between the rows of staples. This type of surgical stapler minimizes bleeding by applying the outside rows of staples to layers of surrounding tissue as the cutting means pierces through the tissue in between the staples. In such a stapler, if it is not recognized that a spent cartridge is in the stapler the user may attempt to cut tissue without the staples being inserted alongside the incision made by the knife.
As a result of the concern about such occurrences there have been attempts made in the art to provide such disposable surgical staplers with locking mechanisms that reduce possible delays or potential harm to a patient. Unfortunately, the locking mechanisms of these staplers are not inexpensive, simple, or necessarily reliable.
For example, Green, U.S. Pat. No. 4,086,926 (hereinafter "Green") describes a stapler that has a cartridge that contains a means for locking itself during shipment and preventing the inadvertent severing of organic structures when all of the staples, for example, have been expelled from the cartridge. Green describes a complex staple cartridge locking system that is embodied in the cartridge. The Green cartridge includes the following; a rail assembly, an anvil means, an elongate main body, a pair of belts mounted in the elongate main body, a plurality of surgical staples carried by the above-mentioned belts, a pair of pushers, ramp means, a knife, and shifter means associated with the knife. Since the cartridge has all these elements in it it is complex and relatively expensive to manufacture.